FANCJ DNA helicase is recruited to the replisome by AND-1 to ensure genome stability.

FANCJ, a DNA helicase linked to Fanconi anemia and frequently mutated in cancers, counteracts replication stress by dismantling unconventional DNA secondary structures (such as G-quadruplexes) that occur at the DNA replication fork in certain sequence contexts. However, how FANCJ is recruited to the replisome is unknown. Here, we report that FANCJ directly binds to AND-1 (the vertebrate ortholog of budding yeast Ctf4), a homo-trimeric protein adaptor that connects the CDC45/MCM2-7/GINS replicative DNA helicase with DNA polymerase α and several other factors at DNA replication forks. The interaction between FANCJ and AND-1 requires the integrity of an evolutionarily conserved Ctf4-interacting protein (CIP) box located between the FANCJ helicase motifs IV and V. Disruption of the CIP box significantly reduces FANCJ association with the replisome, causing enhanced DNA damage, decreased replication fork recovery and fork asymmetry in cells unchallenged or treated with Pyridostatin, a G-quadruplex-binder, or Mitomycin C, a DNA inter-strand cross-linking agent. Cancer-relevant FANCJ CIP box variants display reduced AND-1-binding and enhanced DNA damage, a finding that suggests their potential role in cancer predisposition.

Exploring the G-quadruplex binding and unwinding activity of the bacterial FeS helicase DinG.

Despite numerous reports on the interactions of G-quadruplexes (G4s) with helicases, systematic analysis addressing the selectivity and specificity of each helicase towards a variety of G4 topologies are scarce. Among the helicases able to unwind G4s are those containing an iron-sulphur (FeS) cluster, including both the bacterial DinG (found in E. coli and several pathogenic bacteria) and the medically important eukaryotic homologues (XPD, FancJ, DDX11 and RTEL1). We carried out a detailed study of the interactions between the E. coli DinG and a variety of G4s, by employing physicochemical and biochemical methodologies. A series of G4-rich sequences from different genomic locations (promoter and telomeric regions), able to form unimolecular G4 structures with diverse topologies, were analyzed (c-KIT1, KRAS, c-MYC, BCL2, Tel23, T30695, Zic1). DinG binds to most of the investigated G4s with little discrimination, while it exhibits a clear degree of unwinding specificity towards different G4 topologies. Whereas previous reports suggested that DinG was active only on bimolecular G4s, here we show that it is also able to bind to and resolve the more physiologically relevant unimolecular G4s. In addition, when the G4 structures were stabilized by ligands (Pyridostatin, PhenDC3, BRACO-19 or Netropsin), the DinG unwinding activity decreased and in most cases was abolished, with a pattern that is not simply explained by a change in binding affinity. Overall, these results have important implications for the biochemistry of helicases, strongly suggesting that when analysing the G4 unwinding property of an enzyme, it is necessary to investigate a variety of G4 substrates.

Optimizing fresh-frozen plasma transfusion in surgical neonates through thromboelastography: a quality improvement study.

Fresh frozen plasma (FFP) is largely misused in the neonatal setting. The aim of the study is to evaluate the impact of a Thromboelastography (TEG)-based Quality Improvement (QI) project on perioperative FFP use and neonatal outcomes. Retrospective pre-post implementation study in a level-III NICU including all neonates undergoing major non-cardiac surgery before (01-12/2017) and after (01-12/2019) the intervention. In 2018, the intervention included the following: (1) Training on TEG, (2) Implementation of TEG, and (3) Algorithm for TEG-directed FFP administration in surgical neonates. We compared pre- vs post-intervention patient characteristics, hemostasis, and clinical management. Linear and logistic regression models were used to evaluate the impact of the project on main outcomes. We analyzed 139 neonates (pre-intervention: 72/post-intervention: 67) with a mean (± SD) gestational age (GA) 34.9 (± 5) weeks and birthweight 2265 (± 980) grams which were exposed to 184 surgical procedures (pre-intervention: 91/post-intervention: 93). Baseline characteristics were similar between periods. In 2019, prothrombin time (PT) was longer (14.3 vs 13.2 s; p < 0.05) and fibrinogen was lower (229 vs 265 mg/dl; p < 0.05), if compared to 2017. In 2019, the intraoperative exposure to FFP decreased (31% vs 60%, p < 0.001), while the pre-operative FFP use did not change. The reduction of intraoperative FFP did not impact on mortality and morbidity. Intraoperative FFP use was lower in the post-intervention even after controlling for GA, American Society of Anesthesiologists score, PT, and fibrinogen (Odds ratio: 0.167; 95% CI: 0.070, 0.371).   Conclusion: The TEG-based QI project for the management of FFP during neonatal surgery reduced intraoperative FFP exposure. What is Known: • PT and aPTT are poor predictors of bleeding risk in acquired neonatal coagulopathy, leading to likely unnecessary fresh frozen plasma (FFP) transfusion in the Neonatal Intensive Care Setting.  • As neonatal hemostasis is a delicate balance between the concomitant reduction of pro- and anti-coagulants drivers, thromboelastography (TEG) is a promising alternative for coagulation monitoring. What is New: • The implementation of TEG, training, and shared protocols contributed to reduced intraoperative FFP use, which was not associated with increased mortality or bleeding events. • These findings inform future research showing that there is clinical equipoise to allow for larger studies to confirm the use of TEG in NICUs and to identify TEG cut-offs for transfusion practice.

CNG channel structure, function, and gating: a tale of conformational flexibility.

Cyclic nucleotide-gated (CNG) channels are key to the signal transduction machinery of certain sensory modalities both in vertebrate and invertebrate organisms. They translate a chemical change in cyclic nucleotide concentration into an electrical signal that can spread through sensory cells. Despite CNG and voltage-gated potassium channels sharing a remarkable amino acid sequence homology and basic architectural plan, their functional properties are dramatically different. While voltage-gated potassium channels are highly selective and require membrane depolarization to open, CNG channels have low ion selectivity and are not very sensitive to voltage. In the last few years, many high-resolution structures of intact CNG channels have been released. This wealth of new structural information has provided enormous progress toward the understanding of the molecular mechanisms and driving forces underpinning CNG channel activation. In this review, we report on the current understanding and controversies surrounding the gating mechanism in CNG channels, as well as the deep intertwining existing between gating, the ion permeation process, and its modulation by membrane voltage. While the existence of this powerful coupling was recognized many decades ago, its direct structural demonstration, and ties to the CNG channel inherent pore flexibility, is a recent achievement.

Genomic integrity and mitochondrial metabolism defects in Warsaw syndrome cells: a comparison with Fanconi anemia.

Warsaw breakage syndrome (WABS), is caused by biallelic mutations of DDX11, a gene coding a DNA helicase. We have recently reported two affected sisters, compound heterozygous for a missense (p.Leu836Pro) and a frameshift (p.Lys303Glufs*22) variant. By investigating the pathogenic mechanism, we demonstrate the inability of the DDX11 p.Leu836Pro mutant to unwind forked DNA substrates, while retaining DNA binding activity. We observed the accumulation of patient-derived cells at the G2/M phase and increased chromosomal fragmentation after mitomycin C treatment. The phenotype partially overlaps with features of the Fanconi anemia cells, which shows not only genomic instability but also defective mitochondria. This prompted us to examine mitochondrial functionality in WABS cells and revealed an altered aerobic metabolism. This opens the door to the further elucidation of the molecular and cellular basis of an impaired mitochondrial phenotype and sheds light on this fundamental process in cell physiology and the pathogenesis of these diseases.

Two further patients with Warsaw breakage syndrome. Is a mild phenotype possible?

BACKGROUND: Warsaw Breakage Syndrome (WABS) is an ultra rare cohesinopathy caused by biallelic mutation of DDX11 gene. It is clinically characterized by pre and postnatal growth delay, microcephaly, hearing loss with cochlear hypoplasia, skin color abnormalities, and dysmorphisms. METHODS: Mutational screening and functional analyses (protein expression and 3D-modeling) were performed in order to investigate the presence and pathogenicity of DDX11 variant identified in our patients. RESULTS: We report the clinical history of two sisters affected by WABS with a pathological mytomicin C test carrying compound heterozygous mutations (c.2507T > C / c.907_920del) of the DDX11 gene. The pathogenicity of this variant was confirmed in the light of a bioinformatic study and protein three-dimensional modeling, as well as expression analysis. CONCLUSION: These findings further extend the clinical and molecular knowledge about the WABS showing a possible mild phenotype without major malformations or intellectual disability.

Molecular and Cellular Functions of the Warsaw Breakage Syndrome DNA Helicase DDX11.

DDX11/ChlR1 (Chl1 in yeast) is a DNA helicase involved in sister chromatid cohesion and in DNA repair pathways. The protein belongs to the family of the iron⁻sulphur cluster containing DNA helicases, whose deficiencies have been linked to a number of diseases affecting genome stability. Mutations of human DDX11 are indeed associated with the rare genetic disorder named Warsaw breakage syndrome, showing both chromosomal breakages and chromatid cohesion defects. Moreover, growing evidence of a potential role in oncogenesis further emphasizes the clinical relevance of DDX11. Here, we illustrate the biochemical and structural features of DDX11 and how it cooperates with multiple protein partners in the cell, acting at the interface of DNA replication/repair/recombination and sister chromatid cohesion to preserve genome stability.

The permeation mechanism of organic cations through a CNG mimic channel.

Several channels, ranging from TRP receptors to Gap junctions, allow the exchange of small organic solute across cell membrane. However, very little is known about the molecular mechanism of their permeation. Cyclic Nucleotide Gated (CNG) channels, despite their homology with K+ channels and in contrast with them, allow the passage of larger methylated and ethylated ammonium ions like dimethylammonium (DMA) and ethylammonium (EA). We combined electrophysiology and molecular dynamics simulations to examine how DMA interacts with the pore and permeates through it. Due to the presence of hydrophobic groups, DMA enters easily in the channel and, unlike the alkali cations, does not need to cross any barrier. We also show that while the crystal structure is consistent with the presence of a single DMA ion at full occupancy, the channel is able to conduct a sizable current of DMA ions only when two ions are present inside the channel. Moreover, the second DMA ion dramatically changes the free energy landscape, destabilizing the crystallographic binding site and lowering by almost 25 kJ/mol the binding affinity between DMA and the channel. Based on the results of the simulation the experimental electron density maps can be re-interpreted with the presence of a second ion at lower occupancy. In this mechanism the flexibility of the channel plays a key role, extending the classical multi-ion permeation paradigm in which conductance is enhanced by the plain interaction between the ions.

The gating mechanism in cyclic nucleotide-gated ion channels.

Cyclic nucleotide-gated (CNG) channels mediate transduction in several sensory neurons. These channels use the free energy of CNs' binding to open the pore, a process referred to as gating. CNG channels belong to the superfamily of voltage-gated channels, where the motion of the α-helix S6 controls gating in most of its members. To date, only the open, cGMP-bound, structure of a CNG channel has been determined at atomic resolution, which is inadequate to determine the molecular events underlying gating. By using electrophysiology, site-directed mutagenesis, chemical modification, and Single Molecule Force Spectroscopy, we demonstrate that opening of CNGA1 channels is initiated by the formation of salt bridges between residues in the C-linker and S5 helix. These events trigger conformational changes of the α-helix S5, transmitted to the P-helix and leading to channel opening. Therefore, the superfamily of voltage-gated channels shares a similar molecular architecture but has evolved divergent gating mechanisms.

The E3 ubiquitin ligase MID1/TRIM18 promotes atypical ubiquitination of the BRCA2-associated factor 35, BRAF35.

MID1/TRIM18 is a member of the TRIM family of ubiquitin E3 ligases characterized by the presence of a conserved RING-containing N-terminal tripartite motif. Mutations in the MID1 gene have been associated with the X-linked form of Opitz Syndrome, a developmental disorder characterized by midline defects and intellectual disability. The effect of MID1 E3 ligase activity within the cell and the role in the pathogenesis of the disease is still not completely unraveled. Here, we report BRAF35, a non-canonical HMG nuclear factor, as a novel MID1 substrate. MID1 is implicated in BRAF35 ubiquitination promoting atypical poly-ubiquitination via K6-, K27- and K29-linkages. We observed a partial co-localization of the two proteins within cytoplasmic bodies. We found that MID1 depletion alters BRAF35 localization in these structures and increases BRAF35 stability affecting its cytoplasmic abundance. Our data reveal a novel role for MID1 and for atypical ubiquitination in balancing BRAF35 presence, and likely its activity, within nuclear and cytoplasmic compartments.

Acute flaccid myelitis associated with enterovirus-D68 infection in an otherwise healthy child.

BACKGROUND: Reporting new cases of enterovirus (EV)-D68-associated acute flaccid myelitis (AFM) is essential to understand how the virus causes neurological damage and to characterize EV-D68 strains associated with AFM. CASE PRESENTATION: A previously healthy 4-year-old boy presented with sudden weakness and limited mobility in his left arm. Two days earlier, he had an upper respiratory illness with mild fever. At admission, his physical examination showed that the child was febrile (38.5 °C) and alert but had a stiff neck and weakness in his left arm, which was hypotonic and areflexic. Cerebrospinal fluid (CSF) examination showed a mild increase in white blood cell count (80/mm3, 41% neutrophils) and a slightly elevated protein concentration (76 gm/dL). Bacterial culture and molecular biology tests for detecting viral infection in CSF were negative. The patient was then treated with intravenous ceftriaxone and acyclovir. Despite therapy, within 24 h, the muscle weakness extended to all four limbs, which exhibited greatly reduced mobility. Due to his worsening clinical prognosis, the child was transferred to our Pediatric Intensive Care Unit; at admission he was diagnosed with acute flaccid paralysis of all four limbs. Brain magnetic resonance imaging (MRI) was negative, except for a focal signal alteration in the dorsal portion of the medulla oblongata, also involving the pontine tegmentum, whereas spine MRI showed an extensive signal alteration of the cervical and dorsal spinal cord reported as myelitis. Signal alteration was mainly localized in the central grey matter, most likely in the anterior horns. Molecular biology tests performed on nasopharyngeal aspirate and on bronchoalveolar lavage fluid were negative for bacteria but positive for EV-D68 clade B3. Plasmapheresis was performed and corticosteroids and intravenous immunoglobulins were administered. After 4 weeks of treatment, the signs and symptoms of AFM were significantly reduced, although some weakness and tingling remained in the patient's four limbs. MRI acquired after 3 weeks showed that the previously reported alterations were no longer present. CONCLUSION: This case suggests that EV-D68 is a neurotropic agent that can cause AFM and strains are circulating in Europe. EV-D68 disease surveillance is required to better understand EV-D68 pathology and to compare various strains that cause AFM.

Combining FRET and optical tweezers to study RhoGTPases spatio-temporal dynamics upon local stimulation.

Local stimulation with optical tweezers has been used to mimic natural stimuli that occur in biological processes such as cell migration or differentiation. Carriers (beads and lipid vesicles) with sizes down to 30 nm can be manipulated with a high spatial and temporal resolution: they are positioned with a sub-micrometric precision on a specific cell compartment and the beginning of the stimulation can be triggered with millisecond precision. RhoGTPases are a Ras-related family of proteins that regulate many different functions including cell polarity, microtubule dynamics and membrane transport pathways. Here we combine local stimulation with FRET microscopy to study RhoGTPases spatial and temporal activation following guidance cue local stimulation. We used two different vectors for local delivery: silica micro-beads and micro-sized lipid vesicles. The experimental methods associated with neuronal growth cone local stimulation are discussed in detail, as well as the analysis methods. Here we present a protocol that enables to study neuronal growth cone cytoskeleton rearrangements in response to a gradient of molecules in a way that better mimics physiological conditions, and it can be similarly applied to each secreted molecule involved in cell signaling.

Actin Waves Do Not Boost Neurite Outgrowth in the Early Stages of Neuron Maturation.

During neurite development, Actin Waves (AWs) emerge at the neurite base and move up to its tip, causing a transient retraction of the Growth Cone (GC). Many studies have shown that AWs are linked to outbursts of neurite growth and, therefore, contribute to the fast elongation of the nascent axon. Using long term live cell-imaging, we show that AWs do not boost neurite outgrowth and that neurites without AWs can elongate for several hundred microns. Inhibition of Myosin II abolishes the transient GC retraction and strongly modifies the AWs morphology. Super-resolution nanoscopy shows that Myosin IIB shapes the growth cone-like AWs structure and is differently distributed in AWs and GCs. Interestingly, depletion of membrane cholesterol and inhibition of Rho GTPases decrease AWs frequency and velocity. Our results indicate that Myosin IIB, membrane tension, and small Rho GTPases are important players in the regulation of the AW dynamics. Finally, we suggest a role for AWs in maintaining the GCs active during environmental exploration.

Vitamin K antagonists in children with central venous catheter on chronic haemodialysis: a pilot study.

BACKGROUND: To date, no study has investigated the use of vitamin K antagonists (VKA) in children undergoing chronic haemodialysis (HD) with a central venous catheter (CVC). METHODS: Consecutive patients aged <18 years with a newly placed tunnelled CVC for chronic HD were enrolled over a 3-year period. Children with active nephrotic syndrome or a history of venous thrombosis received warfarin (VKA group) with therapeutic target international normalised ratios of between 2.0 and 3.0. Patients at standard risk of CVC malfunction were not treated with VKA (standard group). The primary end-point was overall CVC survival. RESULTS: The VKA group consisted of nine patients (median age 10.6 years; range 1.2-15.3 years) with 11 CVC, and the standard group comprised eight patients (11.8 years; 6.1-17.3 years) with ten CVC. The 6- and 12-month CVC survival was significantly longer in the VKA group than in the standard group (100 vs. 60 % and 83.3 vs. 16.7 %, respectively; p < 0.05), with a median survival of 369 and 195 days, respectively (p < 0.05). None of the CVC in the VKA group required removal due to malfunction, as compared to four in the standard group. No major bleeding episodes occurred in either group. CONCLUSIONS: Therapy with VKA would appear to be safe in children on chronic HD and may improve CVC survival in patients at increased risk of CVC thrombosis.

Cdc42 and RhoA reveal different spatio-temporal dynamics upon local stimulation with Semaphorin-3A.

Small RhoGTPases, such as Cdc42 and RhoA, are key players in integrating external cues and intracellular signaling pathways that regulate growth cone (GC) motility. Indeed, Cdc42 is involved in actin polymerization and filopodia formation, whereas RhoA induces GC collapse and neurite retraction through actomyosin contraction. In this study we employed Förster Resonance Energy Transfer (FRET) microscopy to study the spatio-temporal dynamics of Cdc42 and RhoA in GCs in response to local Semaphorin-3A (Sema3A) stimulation obtained with lipid vesicles filled with Sema3A and positioned near the selected GC using optical tweezers. We found that Cdc42 and RhoA were activated at the leading edge of NG108-15 neuroblastoma cells during spontaneous cycles of protrusion and retraction, respectively. The release of Sema3A brought to a progressive activation of RhoA within 30 s from the stimulus in the central region of the GC that collapsed and retracted. In contrast, the same stimulation evoked waves of Cdc42 activation propagating away from the stimulated region. A more localized stimulation obtained with Sema3A coated beads placed on the GC, led to Cdc42 active waves that propagated in a retrograde manner with a mean period of 70 s, and followed by GC retraction. Therefore, Sema3A activates both Cdc42 and RhoA with a complex and different spatial-temporal dynamics.

A structural, functional, and computational analysis suggests pore flexibility as the base for the poor selectivity of CNG channels.

Cyclic nucleotide-gated (CNG) ion channels, despite a significant homology with the highly selective K(+) channels, do not discriminate among monovalent alkali cations and are permeable also to several organic cations. We combined electrophysiology, molecular dynamics (MD) simulations, and X-ray crystallography to demonstrate that the pore of CNG channels is highly flexible. When a CNG mimic is crystallized in the presence of a variety of monovalent cations, including Na(+), Cs(+), and dimethylammonium (DMA(+)), the side chain of Glu66 in the selectivity filter shows multiple conformations and the diameter of the pore changes significantly. MD simulations indicate that Glu66 and the prolines in the outer vestibule undergo large fluctuations, which are modulated by the ionic species and the voltage. This flexibility underlies the coupling between gating and permeation and the poor ionic selectivity of CNG channels.

Continuous positive airway pressure with helmet versus mask in infants with bronchiolitis: an RCT.

BACKGROUND: Noninvasive continuous positive airway pressure (CPAP) is usually applied with a nasal or facial mask to treat mild acute respiratory failure (ARF) in infants. A pediatric helmet has now been introduced in clinical practice to deliver CPAP. This study compared treatment failure rates during CPAP delivered by helmet or facial mask in infants with respiratory syncytial virus-induced ARF. METHODS: In this multicenter randomized controlled trial, 30 infants with respiratory syncytial virus-induced ARF were randomized to receive CPAP by helmet (n = 17) or facial mask (n = 13). The primary endpoint was treatment failure rate (defined as due to intolerance or need for intubation). Secondary outcomes were CPAP application time, number of patients requiring sedation, and complications with each interface. RESULTS: Compared with the facial mask, CPAP by helmet had a lower treatment failure rate due to intolerance (3/17 [17%] vs 7/13 [54%], P = .009), and fewer infants required sedation (6/17 [35%] vs 13/13 [100%], P = .023); the intubation rates were similar. In successfully treated patients, CPAP resulted in better gas exchange and breathing pattern with both interfaces. No major complications due to the interfaces occurred, but CPAP by mask had higher rates of cutaneous sores and leaks. CONCLUSIONS: These findings confirm that CPAP delivered by helmet is better tolerated than CPAP delivered by facial mask and requires less sedation. In addition, it is safe to use and free from adverse events, even in a prolonged clinical setting.

Reduction in catheter-related infections after switching from povidone-iodine to chlorhexidine for the exit-site care of tunneled central venous catheters in children on hemodialysis.

Only a few studies have investigated the optimal exit site management of tunneled central venous catheters (CVCs) in pediatric patients on chronic hemodialysis (HD). The aim of this study was to assess the efficacy of chlorhexidine solutions and a 5% povidone-iodine solution on the incidence of CVC-related infections in children on HD. The incidence of exit-site infection (ESI), tunnel infection (TI), and bloodstream infection (BSI) was assessed in two groups of tunneled CVCs. The iodopovidone group consisted of 14 CVCs used between 1 January 2011 and 30 June 2012 in 10 children, whose median age at the time of CVC placement was 11.8 years (range 1.2-19.2): 5% povidone-iodine was used for CVC exit-site care. From 1 August 2012 to 31 January 2014, 0.5% chlorhexidine gluconate/70% isopropyl alcohol was used for the exit site, and 2% chlorhexidine gluconate/70% isopropyl alcohol spray for the hub in 13 CVCs was used in 10 patients (chlorhexidine group), whose median age at the time of CVC placement was 10 years (range 1.2-19.2). Ten episodes of ESI were diagnosed in the iodopovidone group (incidence 3.4/1000 CVC days), and only one in the chlorhexidine group (incidence 0.36/1000 CVC days, P = 0.008). One TI was observed in the iodopovidone group (0.34/1000 CVC days), and none in the chlorhexidine group. The incidence of BSIs decreased from 1.7/1000 CVC days (5 cases) to 0.36/1000 CVC days (1 case, P = 0.06) after switching to chlorhexidine. Two CVCs were lost due to CVC-related infections in the iodopovidone group, whereas no CVC was lost due to infections in the chlorhexidine group. In comparison with 5% povidone-iodine, the use of chlorhexidine gluconate was associated with a reduction in the incidence of ESI, TI, and BSI in children on HD.

Thrombotic storm in a teenager with previously undiagnosed ulcerative colitis.

Venous thrombosis can complicate inflammatory bowel diseases, both in adult and pediatric patients, and a few adult cases of thrombotic storm, ie, thrombosis at multiple sites occurring over a period of a few days to a few weeks, have been described. However, venous thrombosis as the first manifestation of an inflammatory bowel disease is extremely rare. We report the case of a 14-year-old girl presenting with ascites and marked hypertransaminasemia resulting from hepatic vein occlusion (Budd-Chiari syndrome). Despite anticoagulant therapy, in the following days she developed criteria suggestive of thrombotic storm to include cerebral vein, right atrial thrombosis, and bilateral pulmonary embolism. Thrombolytic treatment with recombinant-tissue plasminogen activator was started, with resolution of all venous thromboses and without bleeding complications. Additional examinations revealed a severely active ulcerative pancolitis, which did not respond to medical treatment and required surgery. No thrombophilia abnormality nor other risk factors for thrombosis were detected. We conclude that an underlying inflammatory state, such as ulcerative colitis, should be suspected in pediatric patients with venous thrombosis storm.

TRIM27 negatively regulates NOD2 by ubiquitination and proteasomal degradation.

NOD2, the nucleotide-binding domain and leucine-rich repeat containing gene family (NLR) member 2 is involved in mediating antimicrobial responses. Dysfunctional NOD2 activity can lead to severe inflammatory disorders, but the regulation of NOD2 is still poorly understood. Recently, proteins of the tripartite motif (TRIM) protein family have emerged as regulators of innate immune responses by acting as E3 ubiquitin ligases. We identified TRIM27 as a new specific binding partner for NOD2. We show that NOD2 physically interacts with TRIM27 via the nucleotide-binding domain, and that NOD2 activation enhances this interaction. Dependent on functional TRIM27, ectopically expressed NOD2 is ubiquitinated with K48-linked ubiquitin chains followed by proteasomal degradation. Accordingly, TRIM27 affects NOD2-mediated pro-inflammatory responses. NOD2 mutations are linked to susceptibility to Crohn's disease. We found that TRIM27 expression is increased in Crohn's disease patients, underscoring a physiological role of TRIM27 in regulating NOD2 signaling. In HeLa cells, TRIM27 is partially localized in the nucleus. We revealed that ectopically expressed NOD2 can shuttle to the nucleus in a Walker A dependent manner, suggesting that NOD2 and TRIM27 might functionally cooperate in the nucleus.We conclude that TRIM27 negatively regulates NOD2-mediated signaling by degradation of NOD2 and suggest that TRIM27 could be a new target for therapeutic intervention in NOD2-associated diseases.